A contrast dye is injected into a vein in the arm, and a series of x-ray films is taken at timed intervals as the material flows through the kidneys, ureters, and bladder. The dye delineates these structures on the x-ray images and reveals any abnormalities. Intravenous pyelography (IVP) is the most common imaging test for the evaluation of the urinary system.
Purpose of the Intravenous Pyelography
- To evaluate the size, shape, structure, and function of the kidneys, ureters, and bladder
- To aid in the diagnosis of urinary tract disorders, such as kidney stones, tumors, recurring infections, cysts, congenital abnormalities, or traumatic injury
- To evaluate blood flow to the kidney and aid in the diagnosis of renovascular hypertension (increased blood pressure due to narrowing of the artery that leads to the kidney)
- To identify damage to the urinary tract from injury or infection and other problems causing kidney malfunction or obstruction
Who Performs It
- A physician or a radiology technician
- This test may not produce adequate visualization of the urinary tract in people with abnormal kidney function (due to poor uptake of the contrast agent by the kidney).
- IVP may not be safe for people with dehydration, significantly impaired kidney function, diabetes, or multiple myeloma (a type of cancer) because the contrast dye can worsen kidney function and may cause renal failure.
- People who have an allergy to shellfish or iodine may experience an allergic reaction to the contrast dye.
- Pregnant women should not undergo this test because exposure to ionizing radiation may harm the fetus.
- The presence of feces, gas, or residual barium from recent contrast x-rays can interfere with visualization of the urinary tract.
Before the Intravenous Pyelography
- Inform your doctor if you have an allergy to iodine or shellfish or if you’ve ever had an adverse reaction to x-ray contrast dyes. You may be given preventive medication to reduce the risk of an allergic reaction.
- Blood tests will be done to evaluate your kidney function.
- You will be given an oral laxative on the night before the test, and an enema or laxative suppository on the morning of the test, to clean the intestines and provide a clearer view on the x-rays.
- Avoid solid foods for 8 hours before the test.
- At the testing facility, you will be given adequate fluids either orally or through an intravenous (IV) line to prevent dye-induced kidney damage.
- You will be asked to disrobe, remove any jewelry, and put on a hospital gown.
- Empty your bladder just before the procedure.
- A lead shield may be placed over the testes in men to block excess radiation. (However, in women it is not possible to shield the ovaries without obscuring the view of the bladder.) You must sign a consent form before the test.
What You Experience
- You will lie on your back on an x-ray table.
- A preliminary x-ray film is taken to ensure that there are no major abnormalities of the kidneys or urinary tract, and that no residual stool obscures visualization of these structures.
- Contrast dye is injected into a vein in your arm. You may feel a brief burning sensation and metallic taste in your mouth after the dye is injected. Report any other symptoms, such as flushing, nausea, or difficulty breathing, to your doctor.
- X-ray films are taken at regular intervals (usually at 1, 5, 10, 15, 20, and 30 minutes after dye injection) to follow the course of the dye as it is filtered from the bloodstream by the kidneys, and then passes through the ureters into the bladder. You may be instructed to change positions to promote the flow of the dye. Remain still as each x-ray is taken to avoid blurring the pictures.
- In some cases, a sequence of x-ray films (a technique called tomography) is used to produce cross-sectional images, or “slices,” through the kidney.
- For several minutes, an inflatable belt containing two balloons that can be inflated may be wrapped around your abdomen and tightened to compress your ureters and keep the dye in your kidneys. This makes it easier to view the collecting systems within the kidney, and causes no discomfort.
- Finally, you will be taken to a bathroom and asked to urinate. A final x-ray film is then taken immediately to visualize the empty bladder and urethra.
- The procedure typically lasts 60 to 90 minutes.
Risks and Complications
- X-ray exams involve minimal exposure to radiation.
- Some people may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, sneezing, vomiting, hives, and occasionally a life-threatening response called anaphylactic shock. Emergency medications and equipment are kept readily available.
- Patients who are dehydrated or those with impaired kidney function, which may occur with aging, high blood pressure, diabetes and heart disease may experience acute renal failure from infusion of the contrast dye. Adequate hydration before the test can reduce this risk.
After the Intravenous Pyelography
- You are encouraged to drink clear fluids to avoid dehydration and help flush the contrast dye out of your system. You may also receive IV fluids for several hours.
- Elderly or debilitated individuals may experience weakness as a result of fasting and the use of laxatives during test preparation, and may need to be assisted when first walking after the test.
- If there are no complications, you are free to leave the testing facility and resume your normal diet and activities.
- Delayed allergic reactions to the contrast dye, such as hives, rash, or itching, may appear 2 to 6 hours after the procedure. If this occurs, your doctor will prescribe antihistamines or steroids to ease your discomfort.
- Blood may collect and clot under the skin (hematoma) at the injection site; this is harmless and will resolve on its own. For a large hematoma that causes swelling and discomfort, apply ice initially; after 24 hours, use warm, moist compresses to help dissolve the clotted blood.
- The doctor will examine the x-ray films for evidence of any abnormalities in the kidneys and urinary tract.
- If a definitive diagnosis can be made, your doctor will recommend an appropriate course of medical or surgical treatment.
- In many cases, additional diagnostic tests—such as a kidney ultrasound, a kidney CT scan, cystoscopy, or retrograde pyelography—may be needed to further evaluate abnormal results.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media